Lovastatin but not enalapril reduces glomerular injury in Dahl salt-sensitive rats

Dahl salt-sensitive (S) rats fed a high salt diet develop hypertension, hyperlipidemia, and progressive renal disease. Previous studies have suggested that lipids may be important in the pathogenesis of glomerulosclerosis in Dahl S rats. To investigate this possibility, Dahl S rats fed 4% NaCl chow were treated chronically with the cholesterol synthesis inhibitor lovastatin. After 22 weeks, lovastatin-treated rats had a 38% reduction in serum cholesterol, a 76% reduction in urine albumin excretion, and one-sixth the incidence of focal glomerulosclerosis compared with vehicle-treated control rats. Blood pressure in lovastatin-treated rats was significantly (p < 0.05) lower than that in vehicle-treated rats both early in the study (4 weeks of treatment) and at the end of the protocol. Lovastatin had no effect on glomerular filtration rate or glomerular ultrafiltration dynamics. The efficacy of angiotensin converting enzyme inhibitors in attenuating proteinuria and experimental glomerular disease may be dependent on sodium intake. Thus, we also investigated the effects of long-term enalapril treatment on glomerular injury in Dahl S rats fed high salt chow. Enalapril treatment (50 or 200 mg/l drinking water) significantly lowered blood pressure in Dahl S rats, but did not significantly affect albuminuria or glomerulosclerosis. Enalapril also had no effect on glomerular hemodynamics. These results suggest that lipids may be important in the development of both glomerular disease and hypertension in Dahl S rats and that angiotensin converting enzyme inhibition may not affect the course of renal disease in a setting of high salt intake.